Is it true we get a smaller amount of nutrients from food now than in the past?

Some people claim the content of nutrients in some foods is largely reduced compared to what it was previously. Is it true we get a smaller amount of nutrients from the food now than in the past?

Several articles (see the references at the bottom of this article) conclude that it is hard to decide whether there have been real changes in the nutrient content in the foods listed in published food composition tables, mainly from the 1950s until today. This is due to lack of documentation on the evaluated foods and the analyses performed. In addition, one can not preclude naturally variation caused by other factors, such as variety, degree of ripeness, way of cultivation, climate and storage.

It is important to distinguish between factual changes and changes in ways of defining, analysing and evaluating results, for instance concerning description of methods, limits of quantification, test samplings, and sampling management. There have been changes in methods (including increased demands for checking the quality in analyses methods) both in minerals, trace elements and some vitamins. Thus it is doubtful whether old and new values can be compared.

During the work with the present Food Composition table, new analytical values were compared with Norwegian data from 1995 and 2006, in the wheat flour report. The report concluded that there was no difference of great importance in the nutrient content compared with 1995. Regarding selenium, one must take into account that grain cultivated in Norway and other Nordic countries is cultivated in soil poor in selenium. A varying percentage of imported grain is added to the flour, depending on the annual production of grain in the Norwegian crops. The variation of selenium in the present Norwegian flour depends on the amount of added imported grain.

References:

  • The National Food Agency in Sweden: «Minskar näringsinnehållet i vår mat?» and «Kommentar till internationella studier om näringsförändringar i livsmedel».
  • Davis et al.: Changes in USDA Food Composition Data for 43 Garden Crops, 1950 to 1999. Journal of the American College of Nutrition, Vol. 23, No. 6(2004), 669–682
  • M.-S. Fan et al.: Evidence of decreasing mineral density in wheat grain over the last 160 years. Journal of Trace Elements in Medicine and Biology 22 (2008) 315–324.
  • F.J. Zhao et al.: Variation in mineral micronutrient concentrations in grain of wheat lines of diverse origin. Journal of Cereal Science 49 (2009) 290–295
  • D. R. Davis: Declining Fruit and Vegetable Nutrient Composition: What Is the Evidence? Hortscience, Vol. 44(1) February 2009